This invention relates to a single lens reflex electric shutter camera with automatic exposure control and of the storage type, and more particularly to an electric shutter circuit which is an improvement over a manual exposure time setting device.
With the prior art electric shutter used in a single lens reflex electric shutter camera of an automatic exposure control and storage type, either the automatic exposure control or manual exposure time setting or adjustment may be selected by a means of a change-over switch.
In the case of the automatic exposure control, a constant current is linearly charged to a time-constant condenser according to the variation in input from a light receiving element in a light measuring circuit. In the case of the manual exposure time setting, the charging characteristics thereof according to the manual exposure time setting variable resistor is dependent on an exponential function of a set resistance, thus resulting in the failure to operate a comparator detector circuit, with the result that there are provided two trigger level adjusting resistors for switching from an automatic mode to a manual mode and vice versa, followed by the adjustment for each case.
In addition to this, the temperature compensation should be separately carried out for the light measuring circuit for automatic mode and for the time constant circuit for manual mode, with difficulties in integrating the above two circuits.
Still furthermore, the manual exposure time setting variable resistor should be selected in a geometrical series manner. However, such a resistor is costly and of poor accuracy, as compared with the variable resistor, whose resistance varies in an arithmetical series manner.